Signal detectors are used in a variety of applications. For example, loss of signal (LoS) and low frequency periodic signaling (LFPS) detectors may be used in communications applications, including those involving the transmission of signals through standards such as a Universal Serial Bus (USB) cable, a display port (DP) interface, a Thunderbolt (TBT) cable, or a converged-IO (CIO), all passing through one connector (e.g., Type-C connector) or different connectors. When used in these applications, LoS and LFPS detectors may detect low-speed or high-speed signals.
In some applications, LFPS and LoS detection is performed in low power modes of a chip used with an interface. Such a chip may, for example, support the high-speed channels of an interface. In this case, LFPS and LoS detection may be performed when the high-speed channels are off or otherwise inactive.
Because high-speed channels consume substantial power, it may be beneficial for the LFPS detector to operate at low power in order to have an offsetting effect. It may also be beneficial to operate at low power (e.g., in one or more low power modes) when a channel is off. It may also be beneficial for an LFPS detector to operate with a fast response, e.g., when used to support a CIO standard having a 3-pulse power-up requirement of the whole high-speed channel including the detector. Also, in some applications, an LFPS detector is directly connected to high-speed pins. In such a case, it may be beneficial for the detector to be implemented in a manner that does not load the high-speed pins. It also may be beneficial for the LFPS detector to perform secondary electrostatic discharge (ESD) protection. LFPS and LoS detectors that currently exist are unable to satisfy these performance standards.